Fiber optic gyroscopes (FOGs) have become widely used technologies in many systems to sense the rotation and angular orientation of various objects, such as aerospace vehicles. FOGs work by directing light in opposite directions around a closed optical path enclosing an area whose normal is along an axis of rotation. If the device is rotated about the axis of rotation, the optical path length for the light traveling in one direction will be reduced, while the optical path length for the light traveling in the opposite direction will be increased. The change in path length causes a phase shift between the two light waves that is proportional to the rate of rotation.
Referring to FIG. 1, a typical FOG 10 includes a light source 15, a rate detector 20, a coupler 25, an integrated optics chip (IOC) 30, and an interferometer, such as a sensing coil 35. As shown in FIG. 1, a red fiber service lead 40 and blue fiber service lead 45 of the IOC 30 is spliced 50, 55 to the red fiber service lead 60 and blue fiber service lead 65 of the fiber coil interferometer 35. Each of these service leads are often approximately two meters in length to allow optical splicing needed in the build process. Since these fiber service leads for splicing are functionally part of the interferometer 35, the manner in which the service leads are stowed is a key gyroscope performance parameter.
In conventional FOG builds, these lead fibers are stowed in a thread-like winding pattern in a holding compartment having independent thermal characteristics from the interferometer 35. Specifically, in such an approach, waves counter-propagating through the coil 35 may “see” different environment effects at different points in time. High-performance polarization maintaining gyroscopes must have Lorentz reciprocity between the counter-propagating waves. Lorentz reciprocity requires light propagating in a medium to have identical effects independent of the direction of light propagation. Environmental effects can easily degrade Lorentz reciprocity and gyroscope performance. As such, these conventional approaches typically have degraded Lorentz reciprocity caused by environmental effects.